Einstein, Pasadena and How a Solar Eclipse Helped Prove the Theory of Relativity

Published : Monday, August 21, 2017 | 5:03 AM

Two things most Pasadenans know: a solar eclipse is predicted to occur today, and, that the world-famous Albert Einstein, creator of the Theory of Relativity, taught at Caltech and lived in Pasadena in the 1930’s. But few likely realize that a solar eclipse played a very large role in Einstein’s famous computations.

The theory of relativity is actually two interrelated theories proposed by Einstein: special relativity, which applies to elementary particles and their interactions, describing all their physical phenomena except gravity; and general relativity, which explains the law of gravitation and its relation to other forces of nature, including his belief that rays of light bend in the presence of a gravitational field.

Dr. Patrick McCarthy, Director of the Pasadena-based Giant Magellan Telescope Project, said it was an eclipse that confirmed Einstein’s theory of General Relativity.

“The sun will bend starlight as it goes by it, but it’s pretty hard to measure the positions of stars right next to the sun because the sun is awfully bright,” McCarthy said last week. “But in the early 1900s, there was an expedition to observe this total solar eclipse in South Africa where the astronomers have gone six months in advance. They ahd taken some deep photographs and measured positions of stars, and then when the sun was between us and those stars and the moon conveniently blocked out the light of the sun, they re-measured the positions of the stars and they could see the light has been bent going around the sun.”

McCarthy was referring to an expedition by a team led by British astronomer Sir Arthur Eddington, who observed the total solar eclipse of May 29, 1919 on an island off the west coast of Africa purposely to attempt to confirm Einstein’s theory.

“That was the first time that the scientific world recognized that there was clear validity to Einstein’s theory of relativity, and it changed the whole way we think about the universe, of gravity, about space and time,” he said. “And that few minutes when the sun was blocked was a crucial time to verify and prove that that theory was more than just a theory; it’s reality.”

A year before, a team of American astronomers led by Samuel Alfred Mitchell tried to test the theory of relativity by observing a solar eclipse from Baker City, Oregon on June 8, 1918, but thick clouds came just as the eclipse neared totality and made the experiment impossible.

The 1919 confirmation, three years after he published the theory in its final form, made Einstein an overnight sensation, and led to his winning the Nobel Prize in 1921.

Dr. Cameron Hummels, Caltech’s Director of Astronomy Outreach, said that confirmation was crucial for science, and was significant for Pasadena, where Einstein spent time when he was fine-tuning his theory of relativity.

“They went to the locations and they found that in fact, yes, the position of the star was warped and it was a major confirmation of the theory of general relativity. And it was a really, really big deal,” Hummels said. “That’s something that I haven’t mentioned a lot of. Maybe it’s too esoteric for people, but it’s had a dramatic implication for our understanding of nature and our understanding of the physical world.”

Hummels said Einstein spent a “substantial amount of time” at the Carnegie Institute (now Carnegie Observatories) on Santa Barbara Street near North Lake Avenue.

“I think he spent three years in Pasadena working in and doing research, a little bit after the general relativity contributions. Einstein has [a]connection with Pasadena,” Hummels added.

McCarthy said Einstein also spent much of his time at the Mount Wilson Observatory as the scientist was formulating the theory of relativity.

Einstein lived in Pasadena with his wife Elsa, spending three winters in the City in 1931, 1932 and 1933, at about the time he was at the height of his fame.

Articles taken from his writings and letters to friends in Germany say he was drawn to Pasadena because of the scientific work and groundbreaking developments coming out of Caltech and the Carnegie Institute.

In 1933, Einstein undertook his third two-month visiting professorship at Caltech, and in 1935 he decided to remain permanently in the United States and apply for citizenship.